The invention relates to novel nematic liquid crystal compounds for electrooptical devices for modulation of the transmitted or incident light and for the rendition of numbers, symbols and images; further as orientation medium in the spectroscopy and gas chromatography.
It is known that nematic liquid crystal compounds can be rearranged in electrical fields and are thus useful for the making of electrooptical devices (M. Tobias. International Handbook of Liquid Crystal Displays 1975-1976 Ovum Ltd. London 1976).
Liquid crystals are also highly useful as orientation medium in the spectroscopy in the visible and near UV field, in the nuclear magnetic resonance spectroscopy as well as in the gas chromatography (G. Meier, T. Sachmann, J. G. Grabmaier, Applications of Liquid Crystals Springer-Verlag, Berlin-Heidelberg-New York 1975).
Heretofore there were used for the mentioned purposes in many cases the substituted benzoic acid phenylesters (economic patent No. 86,269 of the German Democratic Republic; Steinstrasser, Z. Naturforsch, 27b, 774 (1972)). These esters possess a relatively high viscosity which causes undesirably long starting and shut-off times, particularly at low temperatures when used in electro-optical devices. The clearing points are partly undesirably low and the melting points have values which are too high.